linux-kernel - Re: [PATCH V2 1/2] rust: cpu: Introduce CpuId abstraction

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Message-ID: <20250610101849.ymuw4bmjsucsoblp@vireshk-i7>
Date: Tue, 10 Jun 2025 15:48:49 +0530
From: Viresh Kumar <viresh.kumar@...aro.org>
To: Miguel Ojeda <miguel.ojeda.sandonis@...il.com>
Cc: Danilo Krummrich <dakr@...nel.org>,
	FUJITA Tomonori <fujita.tomonori@...il.com>,
	Boqun Feng <boqun.feng@...il.com>,
	"Rafael J. Wysocki" <rafael@...nel.org>,
	Thomas Gleixner <tglx@...utronix.de>,
	Peter Zijlstra <peterz@...radead.org>,
	Miguel Ojeda <ojeda@...nel.org>,
	Alex Gaynor <alex.gaynor@...il.com>, Gary Guo <gary@...yguo.net>,
	Björn Roy Baron <bjorn3_gh@...tonmail.com>,
	Benno Lossin <lossin@...nel.org>,
	Andreas Hindborg <a.hindborg@...nel.org>,
	Alice Ryhl <aliceryhl@...gle.com>, Trevor Gross <tmgross@...ch.edu>,
	Vincent Guittot <vincent.guittot@...aro.org>,
	Yury Norov <yury.norov@...il.com>, rust-for-linux@...r.kernel.org,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH V2 1/2] rust: cpu: Introduce CpuId abstraction

On 10-06-25, 11:43, Miguel Ojeda wrote:
> (By the way, as far as I understand there is no way we could wrap
> going to `i32`, but it may not hurt to add a `debug_assert!` in the
> `u32` constructors.)

Something like this ?

@@ -79,6 +79,7 @@ pub fn from_i32(id: i32) -> Option<Self> {
     #[inline]
     pub unsafe fn from_u32_unchecked(id: u32) -> Self {
         debug_assert!(id < nr_cpu_ids());
+        debug_assert!(id <= i32::MAX as u32);

         // INVARIANT: The function safety guarantees `id` is a valid CPU id.
         Self(id)

-- 
viresh